Light emitting devices such as light emitting diodes and laser diodes using III-V group or II-VI group compound semiconductors may realize various colors such as red, green, blue, and ultraviolet, etc. due to development of thin film growth techniques and light emitting device materials. Efficient white light may be achieved by using fluorescent material or color combination. The light emitting devices such as light emitting diodes and laser diodes may have low power consumption, semi-permanent lifetime, fast response speed, safety and environment friendliness compared to conventional light sources such as fluorescent lamps and incandescent lamps.
Methods of realizing the white light may include a method of coating a fluorescent material on a blue or ultraviolet UV light emitting diode chip in a single chip manner, and a method of producing a white light by forming fluorescent chips and blue or ultraviolet UV light emitting diode chips and combing them with each other in a multichip manner.
As for the multi-chip manner, there is a typical method of manufacturing and combing three kinds of chips of RGB (Red, Green, Blue). In this connection, however, because the operation voltages of the RGB chips are uneven or outputs of the RGB chips are different due to the surrounding conditions, the color coordinates thereof change.
In addition, in order that the white light is realized in the single chip manner, at least one phosphor is excited using light emitted from the blue LED.
In the implementation of the white light using such a phosphor composition, there is continuous attempting to improve the luminance and the color rendering index (CRI). However, it may be not easy to realize the white light having a high color rendering index value without reduction in luminous flux.